The present invention relates to a cassette adaptor for inputting from an external equipment a signal stored in a recording medium other than a cassette tape, in audio equipment mounted on a vehicle where cassette tapes are or has been mainly used.
Among vehicle-mounted audio equipment, the cassette tape recording apparatus is used on many vehicles as audio equipment as popular as the radio tuner. In recent years, with the extended use of compact discs (CD), compact disc reproduction apparatuses are in increasing demand as audio equipments, which are mounted in luxury vehicles. The compact disc reproduction apparatus, however, has so far been difficult to be mounted on an automobile as an additional equipment unless having originally included in the standard equipment of the new automobile. Also the compact disc reproduction apparatus is expensive as compared to the cassette tape reproduction apparatus. For these reasons, the widespread use of the compact disc reproduction apparatus for use on automotive vehicles has been hampered.
Therefore, for listening to music etc. from a compact disc in a vehicle not equipped with a compact disc reproduction apparatus, a portable compact disc reproduction apparatus has been brought into the vehicle and connected with a cassette tape reproduction apparatus of the vehicle-mounted audio equipment for reproduction. Generally, the vehicle-mounted audio equipment has no input terminal for additional equipment, and therefore a cassette adaptor has been used as input means for the signal from the compact disc reproduction apparatus.
In this signal input method using the cassette adaptor, which receives the output signal from the compact disc reproduction apparatus, the cassette adaptor is inserted into a cassette tape insertion slot of the cassette tape reproduction apparatus constituting the vehicle-mounted audio equipment. By inserting the cassette adaptor into a cassette tape insertion slot, the magnetic head incorporated in the cassette adaptor is brought into vicinity of the reproduction head of the cassette tape reproduction apparatus, so that output signal from the compact disc reproduction apparatus leaks from the magnetic head of the cassette adaptor and is transmitted to the reproduction head of the cassette tape reproduction apparatus. As a result, output signal from the portable compact disc reproduction apparatus is input through the cassette adaptor to the vehicle-mounted audio equipment and is reproduced.
An example of the prior art described above is a signal input method disclosed in a Japanese Examined Patent Application, Publication No. HEI-4-56391.
FIG. 12 is a plan view of the conventional cassette adaptor disclosed in the Japanese Examined Patent Application, Publication No. HEI-4-56391. A housing 112 of a cassette adaptor 110 shown in FIG. 12 has substantially the same shape as a housing (cassette case) of the cassette tape. Mounted in an opening 126 in the front face (the lower surface in FIG. 12) of the housing 112 is a 2-channel magnetic head 140. A two-core cable 142 is led out of a notch 146 of the housing 112. An end of the cable 142 is connected to an audio circuit in the housing 112, and the other end is terminated with a plug 144. The plug 144 is configured to be connected to a headphone jack for a compact disc reproduction apparatus not shown. FIG. 13 is an electrical circuit diagram showing an audio circuit disposed in the housing 112.
When listening to music or the like in a vehicle from a compact disc using the conventional cassette adaptor 110 configured as described above, the plug 144 at the other end of the cable 142 is connected to the headphone jack of the compact disc reproduction apparatus. Then the cassette adaptor 110 is inserted into a cassette tape insertion slot of the cassette tape reproduction apparatus mounted on the vehicle. A magnetic head 140 of the cassette adaptor 110 inserted in the cassette tape insertion slot is disposed to oppose a reproduction head 150 of the cassette tape reproduction apparatus. When the compact disc reproduction apparatus is played under such a condition as described above, output signal therefrom is input to the audio circuit shown in FIG. 13 via the cable 142, and is fed to the magnetic head 140. Since the magnetic head 140 is disposed to oppose the reproduction head 150 of the cassette tape reproduction apparatus, the signal input to the magnetic head 140 is sent to the reproduction head 150 of the cassette tape reproduction apparatus.
In case that a compact disc is played by using the conventional cassette adaptor configured as described above, the signal is transmitted most efficiently when the head gap is smallest between the magnetic head 140, which outputs the signal, and the reproduction head 150 of the cassette tape reproduction apparatus, which receives the signal. In case that the centers of the two heads are displaced from each other along the tape running direction, however, the signal transmission efficiency is significantly degraded. Also in case that the heights of the two head cores of the two heads which determine the positions of the tracks on which the tape runs do not agree with the tape width direction, not only the signal transmission efficiency between the heads is degraded but also crosstalk of the reproduced sound from the left channel to the right channel occurs when, for example, the magnetic head on the transmitting side of the left channel approaches the reproduction head of the right channel.